With the help of Leo Szilard, Albert Einstein writes President Franklin D. Roosevelt, alerting the President to the importance of research on nuclear chain reactions and the possibility that research might lead to developing powerful bombs.
Continue to Timeline of Events: 1951 to 1970
The German radiochemists Otto Hahn and Fritz Strassmann discover the process of fission in uranium.
August 2, 1939
Albert Einstein writes President Franklin D. Roosevelt, alerting the President to the importance of research on nuclear chain reactions and the possibility that research might lead to developing powerful bombs. Einstein notes that Germany has stopped the sale of uranium and German physicists are engaged in uranium research.
September 1, 1939
Germany invades Poland. World War II begins.
February 24, 1941
Glenn T. Seaborg’s research group at the University of California in Berkeley discovers plutonium.
May 28, 1941
Roosevelt establishes the Office of Petroleum Coordinator for National Defense, later the Petroleum Administration for War, to issue rules governing the production, transportation, and distribution of petroleum and petroleum products.
December 7, 1941
The Japanese attack Pearl Harbor. The United States enters the war.
January 19, 1942
President Roosevelt approves production of the atomic bomb following receipt of a National Academy of Sciences report determining that a bomb is feasible.
June 17, 1942
President Roosevelt instructs the Army to take responsibility for construction of atomic weapons complex. The Army delegates the task to the Corps of Engineers.
August 13, 1942
The Army Corps of Engineers establishes the Manhattan Engineer District to develop and build the atomic bomb. Uranium isotope separation facilities are built at Oak Ridge, Tennessee; plutonium production reactors are built at Hanford, Washington; and a weapons laboratory is set up at Los Alamos, New Mexico.
September 19, 1942
Brigadier General Leslie R. Groves, head of the Manhattan Engineer District, selects Oak Ridge, Tennessee, site for facilities to produce nuclear materials. Isotope separation of uranium235 takes place in the gaseous diffusion plant built in the K-25 area of the site, in the electromagnetic plant in the Y-12 area, and in the liquid thermal diffusion plant. A pilot pile (reactor) and plutonium separation facility are built and operated at the X-10 area.
November 25, 1942
Groves selects Los Alamos, New Mexico, as site for separate scientific laboratory to design an atomic bomb.
December 2, 1942
Metallurgical Laboratory scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in pile constructed under the west grandstand at Stagg field in Chicago.
January 16, 1943
Groves selects Hanford, Washington, as site for full-scale plutonium production and separation facilities. Three reactors--B, D, and F--are built.
The Big Inch crude-oil pipeline is completed from the Texas oil fields to Pennsylvania. The line serves as a transportation alternative to tankers that are being sunk by German submarines. The line also supplies export petroleum to the East Coast so that the reduced number of tankers can meet the demands of the European war fronts with the shorter-haul distance across the Atlantic.
The Little Big Inch pipeline for refined petroleum products is completed from Texas to New Jersey. Like the Big Inch, it is built by a private company, War Emergency Pipelines, but owned by the Federal government.
April 5, 1944
Congress passes the Synthetic Liquid Fuels Act authorizing the Bureau of Mines to build energy research laboratories.
December 22, 1944
Congress in the Flood Control Act of 1944 confirms the authorization of the Southwestern Power Administration created by President Roosevelt through a series of Executive and Departmental orders.
April 12, 1945
President Roosevelt dies. Harry S. Truman becomes President.
May 7, 1945
July 16, 1945
Los Alamos scientists successfully test a plutonium implosion bomb in the Trinity shot at Alamogordo, New Mexico.
August 6, 1945
The gun model uranium bomb, called Little Boy, is dropped on Hiroshima, Japan.
August 9, 1945
The implosion model plutonium bomb, called Fat Man, is dropped on Nagasaki, Japan. Five days later, Japan surrenders.
June 14, 1946
Bernard Baruch presents the American plan for international control of atomic research to the United Nations. The Soviet Union opposes the plan, rendering it useless.
August 1, 1946
President Truman signs the Atomic Energy Act of 1946 transferring Manhattan Project assets and responsibilities to the civilian Atomic Energy Commission.
January 1, 1947
In accordance with the Atomic Energy Act of 1946, all atomic energy activities are transferred to the newly created Atomic Energy Commission.
August 14, 1947
Ground is broken at the Brookhaven National Laboratory for the Graphite Research Reactor, the first reactor constructed for the sole purpose of exploring peaceful uses of the atom.
Two new production reactors are authorized for the Hanford site. As the Cold War intensifies, the Atomic Energy Commission over the next five years greatly expands the weapons complex. New facilities include three additions to the Oak Ridge gaseous diffusion complex; new gaseous diffusion plants at Paducah, Kentucky, and Portsmouth, Ohio; three additional plutonium production reactors at Hanford; five heavy-water reactors for producing tritium and plutonium at a site on the Savannah River in South Carolina; a reactor testing station near Idaho Falls, Idaho; a feed materials production center at Fernald, Ohio; component and assembly plants at Rocky Flats, Colorado, and Amarillo, Texas; a second weapons laboratory at Livermore, California; and a continental testing site near Las Vegas, Nevada.
June 23, 1948
Soviet Union begins blockade of West Berlin.
August 29, 1949
Soviet Union detonates first atomic device.
January 31, 1950
President Truman instructs the Atomic Energy Commission to expedite development of a thermonuclear weapon.
June 25, 1950
North Korea invades South Korea. The Korean War begins.
October 9, 1950
President Truman approves a $1.4 billion expansion of Atomic Energy Commission facilities to produce uranium and plutonium for nuclear weapons.
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